When your hydroponic system is built, your pumps and timers have been tested and are functioning properly and the nutrient solutions are mixed and tested, you are ready to plant your garden.

Plants that have been raised in soil can be transplanted in a hydroponic garden if the roots are thoroughly rinsed of all soil and organic material but there is always a risk of introducing pests and disease from the nursery where the plants were propagated. There is also a strong possibility that the plants have been overcrowded, over or under watered and generally stressed.

By starting your plants from seed, you have the most control over the initial development of your crop. As a general rule, seeds are free of pests and disease. If you start your seeds in a hydroponic system, there is no transplant stress or shock and minimal chance of disease.

A seed needs moisture and warm temperatures to germinate, which can be provided in your hydroponic garden, or in a system designed for propagation.

Direct seeding into the hydroponic garden is a common method of propagation. Direct seeding works well in perlite, rockwool or any other medium that is fine enough not to loose the seed in. It is important to thoroughly moisten your growing medium prior to seeding.

To seed directly into perlite (or a similar medium) sprinkle the seeds on the moistened perlite and cover with a thin layer of perlite to keep the seeds from drying out. Follow the directions on the seed packet for planting depth.

Rockwool is most often used in the form of cubes for seed propagation. To plant seeds in rockwool, soak the cube in water or nutrient solution and drop the seed into the hole in the center of the rockwool cube. Many growers seed into rockwool cubes and, when the seedling develops, move the whole cube with the plant in it, into the hydroponic garden. A seedling in a rockwool cube can easily be transplanted into an NFT, ebb and flow or drip system.

Once seeded the growing medium will need to be flushed on a regular basis to keep it moist. You can initially use water for germination, right up to the point that the seed coat cracks open and the radical root is exposed. At that point you have a seedling rather than a seed, which will need water, nutrients, light and warmth. The frequency of flushing your growing medium depends on the type of medium you choose. If you are using perlite or rockwool, it will probably need to be flushed every 2 or 3 hours. The medium and the seeds need to be moist.

Controlling temperature is important for good seed germination. Some growers will start their seeds in an incubator, propagation table or similar device to maintain the ideal temperature throughout the germination process. If proper temperatures are not maintained, germination will be delayed or may not happen at all. If you are using an incubator or propagation table, you can seed directly into the growing medium.

When you plant seed for your hydroponic garden, you should over seed by 25 % -50 %. Once your seeds have developed into seedlings, you can select the strongest plants and keep them. The weaker plants can be removed by pinching the plant off at the base. Pulling the plant out will disturb the roots of the plant that you are keeping.

Listed below are some seeds, kits and germinating equipment for you to get started with.